Circaea alpina |
Circaea ×sterilis |
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enchanter's-nightshade, small enchanter's-nightshade |
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Habit | Herbs glabrous or pubescent with at least a few recurved, falcate hairs, glabrous or glandular puberulent distally; stolons with apical tuber. | Herbs glabrous or pubescent with at least a few hairs at nodes; stolons tipped by apical tuber or, more commonly, apex slightly dilated. | ||||
Stems | 3–50 cm. |
7–70 cm. |
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Leaves | petiole 0.3–5 cm; blade usually ovate to broadly ovate, rarely suborbiculate, 1.5–7.5(–11) × 1.5–5.5(–8) cm. |
petiole 0.8–5.5 cm; blade narrowly to broadly ovate, 2–7(–11) × 1.3–4.2(–7) cm, margins denticulate to prom-inently serrate, base cordate, apex short-acuminate to acute. |
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Inflorescences | 0.7–12(–17) cm. |
1.5–18 cm, sparsely to densely stipitate glandular. |
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Flowers | opening before elongation of axis, corymbiform; pedicels erect or ascending at anthesis, 0.7–3.5 mm, with or without a minute, setaceous bracteole at base; floral tube a mere constriction to 0.6 mm, funnelform to very broadly so, nectary wholly within floral tube; sepals white or pink, sometimes purple tinged apically, oblong or ovate to broadly ovate, 0.8–1.8(–2.2) × 0.6–1.3 mm; petals white, obtriangular or obdeltate to obovate or broadly obovate, 0.6–2 × 0.6–1.8 mm; apical notch to 1/2 length of petal; filaments 0.7–2.2 mm; style 0.6–2.3 mm. |
opening after elongation of axis, ± loosely spaced; pedicels ascending to spreading at anthesis, 1.8–5.5 mm, with a minute, setaceous bracteole at base; floral tube 0.4–1.2 mm, funnelform to narrowly so; nectary projecting beyond opening of floral tube, 0.1–0.4 mm; sepals pink or pale green with apex commonly purple tinged, narrowly oblong to oblong-obovate or ovate, 1.6–3.5 × 0.9–2 mm; petals white or pink, narrowly obtriangular to very broadly obovate, base cuneate to rounded, 1–3.6 × (0.6–)1.5–3.6 mm; apical notch (1/3–)1/2–3/4 length of petal; filaments 1.3–3.7 mm, pollen highly sterile (less than 2% fertile); style 2.7–4.7 mm. |
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Capsules | clavoid, tapering smoothly to pedicel, without ribs or grooves, 1.6–2.6 × 0.5–1.2 mm, 1-locular, 1-seeded; pedicel and mature fruit combined length 3.5–7.8 mm. |
sterile, usually aborting before maturity, rarely developing to 3 × 1.5 mm, clavoid to obovoid, somewhat rounded to smooth or with low ribs and shallow grooves, tapering to pedicel, 2-locular, often with one locule larger, each with infertile seed. |
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2n | = 22 (9 bivalents plus a ring or chain of 4, or 11 bivalents at meiosis). |
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Circaea alpina |
Circaea ×sterilis |
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Phenology | Flowering summer. | |||||
Habitat | Moist places in deciduous, mixed, or coniferous forests, especially in naturally disturbed areas along streams. | |||||
Elevation | 0–1000 m. (0–3300 ft.) | |||||
Distribution |
North America; Europe; Asia
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CT; MA; ME; MI; MN; NC; NH; NJ; NY; OH; PA; SD; VA; VT; WI; WV; NB; NS; ON; PE; QC |
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Discussion | Subspecies 6 (2 in the flora). Circaea alpina inhabits moist places, and is also found on moss covered rocks and logs in cold temperate and boreal forests at high altitudes and latitudes throughout the northern hemisphere and in the tropics and subtropics at high elevations in southern and southeastern Asia, at elevations 0–5000 m. (Discussion copyrighted by Flora of North America; reprinted with permission.) |
Circaea ×sterilis is a sterile hybrid intermediate in morphology between C. alpina × C. canadensis. Although sexually sterile, like other hybrids in Circaea, it reproduces more vigorously vegetatively than either of the parents. Its occurrence in naturally disturbed places along streams no doubt results in portions of stolons being broken off and carried away during high water to establish new colonies some distance away; colonies often extend for great distances along streams. The hybrids persist many years and colonies discovered 100 or more years ago can still be found in the same locality, often in the absence of one or both parents. The hybrid also occurs outside the range of C. canadensis subsp. canadensis, most conspicuously on the Gaspé Peninsula, Quebec, and in northern New Brunswick, but also elsewhere. Those hybrids may indicate a once more northerly range for C. canadensis subsp. canadensis, or that seeds resulting from hybridization events can be transported outside the range of the parents by birds or mammals. M. L. Fernald (1950) misapplied the name Circaea canadensis Hill to plants now known to be hybrids (C. ×sterilis) between C. canadensis and C. alpina in North America and placed C. intermedia Ehrhart, a name published later, in its synonymy. Circaea ×intermedia is the hybrid between the European C. lutetiana Linnaeus and C. alpina Linnaeus. Hill used the name C. canadensis for plants in North America, to distinguish them from the European C. lutetiana. (Discussion copyrighted by Flora of North America; reprinted with permission.) |
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Key |
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Source | FNA vol. 10. | FNA vol. 10. | ||||
Parent taxa | Onagraceae > subfam. Onagroideae > tribe Circaeeae > Circaea | Onagraceae > subfam. Onagroideae > tribe Circaeeae > Circaea | ||||
Sibling taxa | ||||||
Subordinate taxa | ||||||
Name authority | Linnaeus: Sp. Pl. 1: 9. (1753) | Boufford: Harvard Pap. Bot. 9: 256. (2005) | ||||
Web links |